This invention relates to a process for removing ammonia from gases, especially gases from coke ovens and for the conversion of the removed ammonia into harmless materials.
In copending application Ser. No. 367,532, filed June 6, 1973 and assigned to the same Assignee as this invention, there is disclosed a process for the removal of ammonia from ammonia bearing gases, especially gases from coke ovens and the conversion of the ammonia into harmless materials. In this process, the ammonia is forced out of the gases by means of an inorganic acid fed into a circulating system and the ammonia salt produced thereby is heated and burned by the addition of a heating medium at a temperature at which only nitrogen and water vapor (steam) are produced as combustion products. The process being such that the resulting acid anhydride which is also formed as a combustion product is fed back, after suitable cooling, into the circulating system containing the washing medium. In this process, two forms of washing solution are disclosed, namely sulfuric acid and hydrochloric acid.
The present invention is directed to perfecting aspects of the process described in the aforesaid copending application Serial No. 367,532, and the present invention concerns a special case where acidic ammonium bisulfite is selected as the inorganic acid which is introduced into the circulating system for washing ammonia out of gases.